FIG. 1 is a longitudinal-sectional view of a conventional dispersion-type EL device wherein 1 indicates a back electrode made of Al foil and the like, 2 indicates an insulator layer, 3 indicates a luminous layer, 4 indicates a transparent electrode, 5 indicates a moisture absorbing film and 6 indicates a moisture-proof film.
The luminous layer in a dispersion-type EL device is usually formed by dispersing phosphor powders of about 10-about 50 .mu.m in particle size in a dielectric cellulosic resin composition dissolved in an organic solvent and coating this dispersion on an insulator layer at a film thickness of about 20--about 70 .mu.m by doctor blade method, silk screening method, etc.
However, according to the above procedure, it is difficult to arrange uniformly the phosphor particles and coat the luminous layer with a smooth surface and there occur spaces between the phosphor particles, resulting in dented portions where the particles are not present, namely, uneven surface of the luminous layer.
In the device made by the conventional method according to which a transparent electrode is formed over the luminous layer of such surface state, it is difficult to apply uniform electrical field to the phosphor particles owing to difference in distance between electrodes and as a result not only scattering of luminance is brought about, but also current is concentrated to the dented portions to cause increase of current density of the EL device and deteriorate the luminous efficiency.
Under the circumstances, the inventors have conducted intensive research in an attempt to obtain a dispersion-type EL device which has a low current density, is excellent in luminous efficiency and is free from uneven luminance. As a result, it has been found that a dispersion-type EL device which satisfies the above requirements can be obtained by filling the dented portions on the surface of the luminous layer with a dielectric resin composition having lower dielectric constant than that of the dielectric resin composition which constitutes the luminous layer, thereby to nearly smoothen the surface of the luminous layer and thereafter producing a usual EL device therefrom. Thus, the present invention has been accomplished.